Dhanbad district was constituted in 1956 by carving out the old Dhanbad subdivision, Chas and Chandankiyari police stations of the Sadar subdivision of the erstwhile Manbhum district. Dhanbad is Police district since 1928. The re-organisation of the districts in the State of Bihar which took place after 1971 did not affect the district of Dhanbad. In 1991 a part of Dhanbad district was sliced away to form Bokaro district.
The district can be divided into three broad natural divisions, viz., (I) the north and north western portions consisting of the hilly region, (ii) the uplands containing coal mines and most of the industries and (iii) the remaining uplands and plains lying to the south of the Damodar river consisting of cultivable flat lands . The north and north western division is separated for the entire length by the Grand trunk road.
In the western middle part of the district are the Dhangi hills, situated in the strip falling between the Grand trunk road in the north and the Grand chord line of the Eastern Rly. In the south, these hills extend from Pradhankhanta to Govindpur, reaching a maximum altitude of 1,256 feet at Dhangi. Further north, a branch of the Parasnath hill runs through Topchanchi and Tundi, the highest point of 1,500 feet being reached at Lalki. The southern part of the district is largely comprised of undulating land. The general slope is from west to east, the direction followed by the two major rivers, Damodar and Barakar.
The Damodar is the most important river of the Chotanagpur plateau. It rises in Palamu and flows eastward between the plateaus of Ranchi and Hazaribag. It is joined by the Bokaro, the Konar and the Barakar rivers. The Damodar enters Dhanbad district at its confluence with the Jamuria, a stream which marks the western boundary of Dhanbad with Hazaribagh District. Further east, the Damodar is joined by the Katri River which rises in the foot hills below Parasnath and traverses through the Coal-field Area. The Damodar flows for about 77 Km. through the district being joined by the Barakar at its eastern border near Chirkunda. The Panchet dam extending to roughly 6 Kms. is built on river Damodar. The hydel station there generates 40,000 K.W. per hour.
The Barakar, which forms the northern boundary of the district, traverses about 77 Kms. In the district. It flows in south westerly direction up to Durgapur and then south till it joins the Damodar near Chirkuda. The Maithon dam is located on this river about 13 Kms. off its confluence with the Damodar. Attached to it is the Maithan Power Station with a generating capacity of 60,000 K.W.H.
Among other small rivers in the district are Gobai, the Irji, the Khudia besides the river Katri.
The climate of the district is characterised by general dryness. It is very pleasant during the cold weather from November to February. Thereafter the climate becomes warm. It remains hot until the monsoon breaks towards the middle of June. With the setting in of rains the temperature falls and humidity rises, July to October are the rainy months. July and August are the wettest months. The average rainfall during July is 287 mm and that in August 445 mm. The average annual rain fall in the district is approximately 1300mm.